What's the difference between scoria and scoriae?

Scoria

Definition:

• (n.) The recrement of metals in fusion, or the slag rejected after the reduction of metallic ores; dross.
• (n.) Cellular slaggy lava; volcanic cinders.

Example Sentences:

• (1) Scoria (volcanic cinder) was most effective in excluding roots of crested wheatgrass and streambank wheatgrass.

Scoriae

Definition:

• (pl. ) of Scoria

Example Sentences:

• (1) Scoria (volcanic cinder) was most effective in excluding roots of crested wheatgrass and streambank wheatgrass.